• International Journal of Vascular Biomedical Engineering
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• v.4 no.2
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• pp.1-6
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• 2006

Microsystems create new opportunities for conventional cell analysis by combining microfluidics and flow cytometry. This article describes recent developments in conventional flow cytometers and related microfluidic flow cytometers to detect, analyze, and sort cells or particles. Flow cytometry strongly consisted of fluidics, optics and electronics requires a large space to equip various components, which are mostly the fluidic components such as compressor, fluid handling system. Adopting microfluidics into flow cytometry enables volume- and power-efficient, inexpensive and flexible analysis of particulate samples. In this paper, we review various efforts that take advantage of novel techniques to build microfluidic cell analysis systems with high-speed analytical capability. Highly integrated microfluidic cytometry shows great promise for basic biomedical and pharmaceutical research, and robust and portable point-of-care devices could be used in clinical settings.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.32 no.12
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• pp.1102-1106
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• 2008

Microfluidics deals with the behavior, precise control and manipulation of fluids at a micro scale. It has become increasingly prevalent in various applications such as biomedical applications (diagnostics, therapeutics, and cell/tissue engineering), inkjet head, and fuel cells etc. The issue of inspection and characterization of microfluidics has emerged as a major consideration in design, fabrication, and detection of microfluidic devices. In this paper, we characterize a diffusion based mixing in Y-microchannel using a fluorescent optical scanner based on a DVD pick-up module, which is widely used in optical storages. Using fluorescent dye, we measure the fluorescent intensity that represents the mixing patterns in Y-microchannel. We also compare these experimental results with computational fluid dynamics (CFD) simulation ones. It is shown that the proposed optical scanner can be used as an alternative measurement system with high performance and cost-effectiveness, compared to conventional optical tools such as epifluorescent microscopes using high resolution CCD camera and confocal microscopes with photomultiplier (PMT) detectors.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.57 no.1
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• pp.137-141
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• 2008

Biochip, which implements bioanalytical process on a tiny surface, is one of candidates for medical diagnosis, drug screening, and molecular sensing. In general, a type of biochip based on microfluidics is composed of microcomponents including microchannel, pump, and valve, which require complicated processes. In this study, gray-scale photolithography(GSPL) was applied to fabricate a biochip with multiple layers. A mould for casting PDMS(polydimethylsiloxane) channel, was fabricated using GSPL. A gray-photomask was prepared by printing gray patterns on a high-quality glossy paper followed by photoreducing by 10:1 onto the photo-film. The formation of multiple layers was studied according to the change of gray level of pattern and the developing time. A biochip composed of a weir(multiple layer structure) and a reaction chamber in a single microchannel was fabricated in a glass plate. Finally, we investigated the application of biochip to antigen-antibody reaction by packing the microbead coated with antibody.

• Proceedings of the KSME Conference
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• 2008.11a
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• pp.1683-1684
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• 2008

For direct detection of microbes in air, samples have to be collected but environmental particles such as dust are also trapped in such samples. Therefore the isolation of target bacteria from non-biological materials of similar size is of great importance in the identification of such organisms. Dielectrophoresis is an emerging technique that can rapidly separate cells in microfluidics. In this paper we proposed a new method for the separation of airborne microbes using condensation and dielectrophoresis. This system could be used as a continuous flow through separation system for various particles and utilized as a pretreatment technique for microbe detection.

• Journal of Electrical Engineering and Technology
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• v.6 no.3
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• pp.402-407
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• 2011

The current paper describes a simpler ground-type, single-plate electrowetting configuration for droplet transport in digital microfluidics without performance degradation. The simplified fabrication process is achieved with two photolithography steps. The first step simultaneously patterns both a control electrode array and a reference electrode on a substrate. The second step patterns a dielectric layer at the top to expose the reference electrode for grounding the liquid droplet. In the experiment, a $5{\mu}m$ thick photo-imageable polyimide, with a 3.3 dielectric constant, is used as the dielectric layer. A 10 nm Teflon-AF is coated to obtain a hydrophobic surface with a high water advancing angle of $116^{\circ}$ and a small contact angle hysteresis of $5^{\circ}$. The droplet movement of 1 mM methylene blue on this simplified device is successfully demonstrated at control voltages above the required 45 V to overcome the contact angle hysteresis.

• Science of Emotion and Sensibility
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• v.14 no.4
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• pp.525-530
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• 2011

Emotion is composed of various feelings such as pleasure, sorrow, comfortability, and so on. The complicated process of the measurement has long been recognized as a major hindrance for the studies of emotion. Previously, individuals' emotion has mainly been measured by means of self-report, interview, EEG (electroencephalogram), ECG (electrocardiogram), EOG (electroculography), and body temperature. With thanks to nano/micro technologies, the possibility in the development of emotion-on-a-chip (EOC) has begun to be proposed. EOC will make it possible to analyze one's psychological status by taking a drop of blood. Discovery of emotional biomarkers in body fluids, understanding of the correlation between those biomarkers and the results from brain science are prerequisites to validate the EOC technology. In this paper, paper microfluidics are introduced as a good candidate for the EOC. As paper microfluidics is cost-effective and easy to use it is expected to be a useful device for the emotion measurement. We present the design and fabrication process for the simple paper-based microfluidic device and discuss the possible application in the field of measuring the human emotion.

• Journal of the Korean Chemical Society
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• v.59 no.1
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• pp.88-92
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• 2015

• 한국가시화정보학회:학술대회논문집
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• 2002.04a
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• pp.79-84
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• 2002

Most microfluidic devices such as heat sinks for cooling micro-chips, DNA chip, Lab-On-Chip, and micro pumps etc. have microchannels of various size. Therefore, the design of practical microfluidics demands detail information on flow structure inside the microchannels. However, detail velocity field measurements are rare and difficult to carry out. In addition, as the microfluidics expands, accurate understanding of microscale transport phenomena becomes very important. In this research, micro-PIV system was employed to measure the velocity fields of flow inside a micro-channel. We carried out PIV measurements for several microchannels with varying channels width, inlet and outlet shape, filters, CCD camera and ICCD camera, etc. For effective composition of micro-PIV system, first of all, it is essential to understand optics related with micro-imaging of particles and the particle dynamics encountered in micro-scale channel flows. In addition, it is necessary to find the optimal condition for given experimental environment and? micro-scale flow to be investigated. The problems encountered in measuring velocity field of micro-channel flows are discussed in this paper.

• Journal of the Korean Geosynthetics Society
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• v.14 no.1
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• pp.23-32
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• 2015

This paper describes a flow experiment and characteristics of heavy metals based on microfluidics, in order to improve the prefabricated vertical drain system that is possible pollutants removal and soil improvement in soft ground polluted with various pollutants, simultaneously. The result showed that the surface with hydrophobic condition affected large effect on flow velocity pollutants, and pH condition was also influence factor for change of flow velocity. Especially, the flow velocity of lead has risen slightly, when pH was close to basicity in complex heavy metal. This means that lead pollutant can reduce a hydrophobic characteristic in comparison with a copper pollutant.

• Journal of the Microelectronics and Packaging Society
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• v.29 no.4
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• pp.55-61
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• 2022

There is a major interest in diagnostic technology for multiple cancers worldwide. In order to reduce the difficulty of cancer diagnosis, a liquid biopsy technology based on a microfluidic device using trace amounts of biofluids such as blood is being studied. And optical biosensing, which measures the concentration of analytes through fluorescence imaging using biofluids, requires various strategies to improve sensitivity, and specialists and equipment are needed to carry out these strategies. This leads to an increase in diagnostic and production costs, and it is necessary to develop a technology to solve this problem. In this paper, we design and propose a fluorescent multi-cancer diagnostic sensing platform structure that implements passive self-separation technology and molecular recognition activation functions by fluid mixing, only with the geometry and microfluidic phenomena of microchannels based on self-driven flow by capillary force. In order to check the parameters affecting the performance of the plasma separation part of the designed sensor, the hydrodynamic diameter of the channel and the viscosity of the fluid were set as variables to confirm the formation of plasma separation flow through simulation. And finally, we propose an optimal sensor platform structure.